1. Field of the Invention
This invention relates to a recording head and an ink jet recording apparatus having the recording head wherein ink is discharged to form droplets of the ink and the droplets are caused to adhere to a recording medium such as paper to thereby accomplish recording.
2. Related Background Art
The ink jet recording method is a recording method whereby ink (recording liquid) is discharged from an opening provided in a recording head and is caused to adhere to a recording medium such as paper to thereby accomplish recording, and has the numerous advantages that very little noise is produced, that high-speed recording is possible, that plain paper can be used and that recording paper of special construction is not required. Ink jet recording heads and ink jet recording apparatus of various types have heretofore been devised. As shown in FIG. 1 of the accompanying drawings, an ink jet recording apparatus according to the prior art is provided with a restoring system as shown in FIG. 2 for the purposes of filling a liquid chamber with ink during the interchange of a head and preventing unsatisfactory discharge or non-discharge, or recovering the apparatus from unsatisfactory discharge. That is, when the head 52 is to be filled up with ink during the interchange of the head, a cap 51 may be brought into intimate contact with a front face plate 56 in FIG. 1, negative pressure may be generated in the cap 51 by negative pressure generating means or a suction pump 57, and ink may be poured into the head through a supply tube 58 communicated with an unshown ink tank, a liquid chamber 53 and liquid paths 54 in the named order and discharged from an orifice 55.
Now, the means of multiplying the discharge port 55 is adopted to improve the recording speed of the ink jet recording apparatus, but, for example, if an attempt is made to fill such a head with ink by the above-described method, the ink will flow out from the discharge port communicated with the liquid path in the lower portion before the ink completely fills up the interior of the liquid chamber. Because the liquid path row and the liquid chamber are long, a bubble 59 will sometimes remain in the liquid chamber 53 as shown in FIGS. 2 and 3 of the accompanying drawings. Such a bubble 59 cannot completely be removed even if the performance of the pump when supplying the ink to liquid chamber 3 by the pump is improved. In some cases, the adherence of the bubble 59 to the rear end of the liquid paths 54 (which is adjacent to the liquid chamber 53) has caused non-discharge and mal-discharge of the ink.
U.S. Pat. No. 4,158,847 discloses a printer head having air bubbles in an ink distributor device. However, this configuration also fails to resolve the above-stated drawbacks. Besides, in some occasions, owing to the vibration of the device, air bubbles in the ink distributor device would enter the ink passage. Thus the ink discharge is deteriorated.